If you're concerned about flooding hazards now across parts of Cape Ann and the North Shore, just wait — it's going to get a whole lot worse, according to a study released last week by the U.S. Geological Survey.
Scientists say that the North Shore is part of a unique, 600-mile-long "hot spot" along the Atlantic Coast where sea levels are rising at a significantly faster rate than the world as a whole — three to four times faster. The hot spot stretches down the Atlantic Coast from north of Boston to North Carolina.
"Flooding right now is an annoyance, but it will be more of an annoyance and bad enough that you'll think twice about parking your car in the driveway if there's a storm coming and it's the spring tide," said Peter Howd, a co-author on the study and a contracted oceanographer with the U.S. Geological Survey.
Since about 1990, sea-level rise in the 600-mile hot spot has increased by 2 millimeters to 3.7 millimeters per year; the global increase over the same period was 0.6 to 1 millimeter per year, according to the study.
As a result, scientists predict that sea levels in the northeast Atlantic will rise 8 to 11.4 inches more than the global average by 2100. That is over and above the 2- to 3-foot rise in sea level that many scientists expect to occur globally over that span.
Although areas north of Boston are "on the low end of the range we're talking about," the North Shore is still facing a dramatic increase in the number of significant flooding events, Howd said.
"That additional 1 foot of water could be enough so that smaller storms cause chronic coastal flooding, as opposed to an acute event like a hurricane," said Howd, who has family on the North Shore.
Yet, Martin Pillsbury, director of environmental planning at the Metropolitan Area Planning Council, notes that few cities or towns have taken any steps toward dealing with potentially rising seas.
"Most communities don't have the chance to dig in and take stock of this because they are more focused on the short term, the budget crunches and all of the other things you have to get done on a local level," Pillsbury said. "There are so many short-term problems and pressures that if you can put it on the back burner, that's what will happen."
About a month ago, the planning council received authorization to use $80,000 from a federal grant to develop what it calls the Regional Climate Change Adaptation Strategy.
Part of the program will be to conduct a vulnerability assessment using existing data to determine more specific implications of higher sea levels and climate change for eastern Massachusetts. The MAPC will also research best practices and policies from cities such as Boston and New York City — which are further along in preparing for higher sea levels — and adapting them to fit smaller communities on the North Shore.
Boston, for instance, is already taking inventory of low-lying areas, is inspecting thousands of sewer and storm drains, has instructed departments to take rising water levels into account during planning, and has taken measures to help businesses prepare for higher seas.
"Based on what our models are saying, there is pretty good agreement that the signal (fastest rates of acceleration) is moving north," Howd said.
In lay terms, the sea-rise rates are tied to the speed of circulation in the Atlantic Ocean. As more ice melts in Greenland, the water becomes colder, slowing down circulation even more and increasing the rate in which ocean levels rise around the northeast coast, he said.
Jesse Roman can be reached at firstname.lastname@example.org.